Pilots and regular readers know that a NOTAM (NOtice To Air[wo]Men) is a little bulletin describing a change to facilities, airspace or procedures that isn't published on the current charts and publications. They look boring. They can be tedious and repetitive to read. Most of them won't pertain to your operation. If you fly out of some little flat bit of the wilderness airport there's probably a NOTAM about the airport lighting being unserviceable from shortly after the snow melts until whenever it is that gophers go back into hibernation.
You can look them up here for Canada if you know your airport identifier. They look like this.
110478 CYHZ CHURCH LAKE(WATER)
CHL3 AMEND PUB: OPR TEL TO READ 902-644-3604
110792 CYHZ AMHERST(HELI)
CCB3 AMEND PUB: NEW WIND FARM 15 TURBINES 0.7 NM RADIUS 455002N 641504W (APRX 1.8 NM NNW AD) 454 FT AGL 483 FT MSL. LGTD NOT PAINTED
110796 CYHZ STANLEY
CCW4 AMEND PUB: NEW TOWER 445602N 635751W (APRX 10 NM SSW AD) 299 FT AGL 988 MSL. NOT LGTD AND NOT PAINTED
110817 CYHZ NEW GLASGOW(ABERDEEN HOSP)(HELI)
OBST LGT U/S 12 TOWERS AT WINDFARM WITHIN 2.7 NM RADIUS 453359N 625746W (APRX 13 NM WNW AD) 377 FT AGL 1460 MSL
1111301630 TIL 1202291600
110844 CYHZ TRENTON
CYTN RNAV(GNSS) RWY 07, RNAV(GNSS) RWY 25 AND NDB RWY 25 APCH: RESTRICTED OPS SPEC 099 OR 410 REQUIRED AD VISUAL SFC NOT ASSESSED CREWS MUST BE FAMILIAR WITH AD ENVIRONMENT
1112151230 TIL APRX 1203161800
110845 CYHZ DEBERT
CCQ3 RNAV(GNSS) RWY 09 AND RNAV(GNSS) RWY 27 APCH ARE RESTRICTED. OPS SPEC 099 OR 410 REQUIRED. AD VISUAL SFC NOT ASSESSED. CREWS MUST BE FAMILIAR WITH AD ENVIRONMENT
1112151230 TIL APRX 1203161800
That's less than half of the Halifax NOTAMs this afternoon. If you're really operating out of Halifax you need to read them all, plus all the ones for the place you are going, and the ones covering airspace you'll be passing through, and possible diversion airports. The float plane guys don't care about the GNSS approaches. The airlines don't care about the windfarms. No one on wheels cares about the change in the operator's telephone number for the Church Lake waterdrome, but they are filed by the order they were filed in, and no one has realized the safety benefit of somehow filtering or classifying them.
They're a fairly often neglected aspect of flight planning. If you're flying between familiar aerodromes on a regular basis, there's a strong temptation to skip them. The flight briefers don't give them unless you ask. (And I still haven't forgiven the briefer I asked for NOTAMs for a flight from Meadow Lake to Buffalo Narrows, who neglected to tell me that the airspace I was chartered to fly through was in use by the Canadian military and their international guests for fighter jet exercises. It's the only time I've called and asked to speak to the supervisor of someone paid to provide me with flight services.) I have fielded a phone call from an airborne coworker who sighted vehicles working in the vicinity of his destination runway, "Avi, could you please check and see if there's a NOTAM ..." (There was).
So I can see how if you were conducting an operation that wasn't actually legal in the first place, transporting certain agricultural products, for example, that you just might not bother to check them. But these folks would have had a better day had they done so. A US reader will probably clarify the difference, but the Americans do have what I'm going to term a special relative of the NOTAM called the TFR (Temporary Flight Restriction) which highlights what in Canada would be NOTAMs restricting airspace to certain operations. They probably did this because people were missing NOTAMs and ending up on the windshield of Air Force One, but what it probably does is make the problem worse, with people clicking on the fun little map that tells you where they don't want you flying today (hey, is President Obama in Seattle today?) and then figuring that covers the important stuff and not going through to the boring list of nav aid outages.